Determination of Soil-Available Micronutrients using the DTPA and Mehlich 3 Methods for Greek Soils Having Variable Amounts of Calcium Carbonate

摘要

The Mehlich 3 method for the extraction of available micronutrients, such as copper (Cu), iron (Fe), manganese (Mn), and zinc (Zn), is more advantageous compared to the diethylene triamine pentaacetic acid (DTPA) method, because it can also be used for the extraction of macronutrients. The aim of this study was to compare the Mehlich 3 and DTPA methods for 172 soils in Greece having different levels of pH and calcium carbonate. Single and multiple regression analyses were employed to evaluate the relationship between Mehlich 3 and DTPA tests. Mehlich 3 results correlated well with DTPA-extractable Cu and Zn, but the correlation was poor for DTPA-extractable Mn. Also, a high correlation was found between Mehlich 3 and DTPA-extractable Fe for calcareous soils (R-2=0.89), while a moderate relationship was found for noncalcareous soils (R-2=0.65), which was improved to 0.78 when the pH was taken into account in multiple regression analysis.